package servlets;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * Servlet implementation class ValidimgServlet
 */

//这是程序是取回动态生成的验证码图片程序

@WebServlet("/GetyanzhengmaImgServlet")
public class GetyanzhengmaImgServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public GetyanzhengmaImgServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		//response.getWriter().append("Served at: ").append(request.getContextPath());	
		
		System.out.println("进入取验证码图片");
		

		// 设置浏览器不要缓存此图片
		response.setHeader("Pragma", "No-cache");
		response.setHeader("Cache-Control", "no-cache");
		response.setDateHeader("Expires", 0);
		response.setContentType("image/jpeg");
		// 创建内存图像并获得其图形上下文
		int width = 60;
		int height = 20;
		BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);
		Graphics g = image.getGraphics();
		// 产生随机验证码
		// 定义验证码的字符表
		String chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
		char[] rands = new char[4];
		for (int i = 0; i < 4; i++) {
			int rand = (int) (Math.random() * 36);
			rands[i] = chars.charAt(rand);
		}
		// 产生图像
		// 画背景
		g.setColor(new Color(0xDCDCDC));
		g.fillRect(0, 0, width, height);
		// 随机产生120个干扰点
		for (int i = 0; i < 120; i++) {
			int x = (int) (Math.random() * width);
			int y = (int) (Math.random() * height);
			int red = (int) (Math.random() * 255);
			int green = (int) (Math.random() * 255);
			int blue = (int) (Math.random() * 255);
			g.setColor(new Color(red, green, blue));
			g.drawOval(x, y, 1, 0);
		}
		g.setColor(Color.BLACK);
		g.setFont(new Font(null, Font.ITALIC | Font.BOLD, 18));
		// 在不同的高度上输出验证码的不同字符
		g.drawString("" + rands[0], 1, 17);
		g.drawString("" + rands[1], 16, 15);
		g.drawString("" + rands[2], 31, 18);
		g.drawString("" + rands[3], 46, 16);
		g.dispose();
		// 将图像输出到客户端
		OutputStream os = response.getOutputStream();
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		ImageIO.write(image, "JPEG", baos);//将画出的图像，以jpeg格式写入baos
		byte[] buffer = baos.toByteArray();
		response.setContentLength(buffer.length);
		os.write(buffer);
		os.flush();
		os.close();
		
		baos.close();
		
		// 将验证码放到 session 中
		HttpSession session = request.getSession();
		String code=new String(rands);
		session.removeAttribute("checkpicCode");
		session.setAttribute("checkpicCode",code);
		System.out.println("验证码是:"+ code);
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}
